Suction Jet Pump

ABSTRACT

The invention relates to a suction jet pump ( 8 ), consisting of a driving jet nozzle ( 10 ), a mixing tube ( 11 ), an intake opening ( 12 ), a working-fluid line ( 7 ) connected to the driving jet nozzle ( 10 ), and a valve ( 9 ) which is arranged with the working-fluid line ( 7 ) and whose housing ( 13 ) has an inlet ( 14 ) and an outlet ( 15 ). A throughflow opening ( 17 ) with a valve body ( 18 ) on both sides of the throughflow opening ( 17 ) is arranged in the housing ( 13 ) in such a way that the throughflow opening ( 17 ) can be closed on both the inlet side and the outlet side, and that at least one spring ( 25, 27, 28 ) is arranged inside the housing ( 13 ) in such a way that it holds the valve body ( 18 ) in a position closing the throughflow opening ( 17 ) on the outlet side until the system pressure is reached.

The subject matter of the invention is a suction jet pump, comprising adriving jet nozzle, a mixing tube, an intake opening, a working-fluidline connected to the driving jet nozzle and a valve which is arrangedin the working-fluid line. Suction jet pumps are used in fuel tanks ofmotor vehicles.

Such suction jet pumps are used in fuel tanks in order to supply fuelfrom various regions of the fuel tank to a feed unit, which feed unitfeeds fuel from the fuel tank to an internal combustion engine of themotor vehicle. In order to drive the suction jet pump, a portion of thefuel fed by the fuel pump is branched off and supplied via theworking-fluid line of the suction jet pump. When starting the internalcombustion engine, the fuel pump should feed fuel in a sufficientquantity to the internal combustion engine as fast as possible. To thisend, a valve is arranged in the working-fluid line, which valve onlyopens when the system pressure is reached so that, particularly in theevent of a starting process, all the fed fuel is first supplied to theinternal combustion engine.

In order to improve the starting behavior of the motor vehicle, it isknown to increase the pressure in the feed line for a short time. Tothis end, the flow rate of the fuel pump is increased for a short timeduring the starting process. However, the effect of the valve in theworking-fluid line is thus cancelled out, which valve is supposed torelease the working-fluid line only when the system pressure is reached.This has the disadvantage that, as a result of the increase in pressure,the valve opens, which valve is supposed to separate the suction jetpump from the fuel supply for the starting process. A portion of thefuel thus reaches the suction jet pump and is not available for theinternal combustion engine. In order to nevertheless ensure a sufficientsupply of the internal combustion engine with fuel during a startingprocess, the fuel pump must be dimensioned such that it, as well as theincreased demand on the internal combustion engine, also supplies theincreased feed quantity for the suction jet pump as a result of theopened valve. These two increased feed quantities lead to anoverdimensioning of the fuel pump. Such fuel pumps require significantlymore space and are more costly.

The object of the invention is therefore to create a suction jet pumpwhich only operates when the fuel supply system operates with systempressure.

According to the invention, the object is achieved in that a throughflowopening is arranged in the housing, that a valve body is arranged onboth sides of the throughflow opening such that the throughflow openingcan be closed both on the inlet side and on the outlet side, and that atleast one spring is arranged within the housing such that it holds thevalve body in a position closing the throughflow opening on the outletside until the system pressure is reached.

The valve arranged in the working-fluid line of the suction jet pump isclosed in the depressurized state in that the spring holds the valvebody on the outlet side in a position closing the throughflow opening.As soon as the fuel pump reaches system pressure, the force acting onthe valve body is larger than the spring force, as a result of which thevalve body is moved out of the position closing the throughflow openingon the outlet side. The valve is thus open and fuel can reach thesuction jet pump. If the pressure rises above the system pressure duringa starting process, the valve body is moved further counter to thespring force until it reaches a position closing the throughflow openingon the inlet side, as a result of which the valve closes. The valveaccording to the invention allows operation of the suction jet pump in apresettable pressure range, wherein the suction jet pump is switched offabove and below this pressure range. This means that the suction jetpump operates only under normal conditions, while, in criticalsituations in which the supply of the internal combustion engine withfuel is supposed to be ensured, the fuel fed by the fuel pump onlyreaches the internal combustion engine. The fuel pump can thus be ofsmaller dimensions since the flow rate of the fuel pump is onlydetermined by the internal combustion engine and the suction jet pump inthe case of system pressure, while in the case of operation of the fuelpump above the system pressure the flow rate is exclusively determinedby the internal combustion engine as a result of the switching off ofthe suction jet pump.

The throughflow opening is of a particularly simple configuration if itis embodied as a diaphragm.

A reliable sealing off is achieved according to another advantageousconfiguration in that the valve body possesses two sealing elementswhich interact on the inlet side and the outlet side with a sealing seatat the throughflow opening.

The sealing elements of the valve body respectively comprise in a simpleand thus low-cost formation an annular disk, which annular disks arearranged on the valve body.

The structure of the valve body is simplified according to anotherconfiguration if the sealing elements are arranged on both sides of thediaphragm relative to the direction of flow such that they surround thethroughflow opening.

A defined position of the valve body in the open position in the case ofsystem pressure is achieved in a further configuration in that a secondspring is arranged relative to the first spring, wherein the firstspring is designed with respect to the opening pressure and the secondspring allows a further movement of the valve body only above the systempressure. In this manner, a movement of the valve body is prevented inthe case of a system pressure in the open position.

The springs used can be both pressure springs and tension springs,wherein the springs are arranged between the housing and the valve body.

Insofar as pressure springs are used, these can also be arranged in adifferent configuration between the valve body and the throughflowopening. For improved guidance and receiving of the pressure springs, ashoulder is formed on the valve body in a further configuration.

The invention is described in greater detail with reference to severalexemplary embodiments. In the drawings

FIG. 1: shows a schematic representation of a fuel tank with a feed unitand a suction jet pump according to the invention,

FIGS. 2 to 4: show a schematic representation of the valve of thesuction jet pump from FIG. 1 in various positions and

FIGS. 5 to 7: show further embodiments of the valve according to FIG. 2.

FIG. 1 shows schematically a fuel tank 1 of a motor vehicle with a feedunit 2 arranged therein for feeding fuel to an internal combustionengine 3. Feed unit 2 has a fuel pump 5 driven by an electric motor 4and is connected via a feed line 6 to internal combustion engine 3. Aworking-fluid line 7 leads from feed line 6 to a suction jet pump 8which feeds fuel to feed unit 2. As well as working-fluid line 7,suction jet pump 8 comprises a valve 9 arranged in working-fluid line 7,a driving jet nozzle 10 connected to working-fluid line 7, a mixing tube11 and an intake opening 12, by means of which fuel is sucked intomixing tube 11 by the fuel escaping from driving jet nozzle 10.

FIG. 2 shows schematically a first embodiment of valve 9 from FIG. 1.The direction of flow is marked by an arrow. Valve 9 comprises a valvehousing 13 with an inlet 14 and an outlet 15. A diaphragm 16 is arrangedin valve housing 13, which diaphragm 16 has a throughflow opening 17.Valve 9 possesses a valve body 18 with two disk-like regions 19, 20which are connected to one another via a central part penetratingthrough throughflow opening 17 such that disk-shaped regions 19, 20 arearranged on the inlet side and outlet side of throughflow opening 17.Both regions 19, 20 have disk-shaped sealing elements 21, 22 whichinteract with sealing seats 23, 24 of diaphragm 16. A pressure spring 25is arranged on the outlet side, which pressure spring 25 moves valvebody 18 counter to the direction of flow. The representation shows thedepressurized state in which no fuel flows through valve 9. As a resultof the spring force, valve body 18 lies on the outlet side againstdiaphragm 16, wherein sealing element 21 interacts with sealing seat 23and thus closes throughflow opening 17.

FIG. 3 shows valve 9 in the case of system pressure. The fuel flowing inwith system pressure via inlet 14 generates a force acting in thedirection of flow, which force opposes the spring force. Pressure spring25 is therein designed such that in the case of system pressure valvebody 18 is moved so far in the direction of flow that both sealingelements 21, 22 are not in contact with sealing seats 23, 24.Throughflow opening 17 is thus free and the fuel can flow through valve9 to outlet 15 and further to the suction jet pump.

FIG. 4 shows valve 9 during a starting process of the internalcombustion engine. Herein, the fuel pump is actuated such that thepressure in the feed line is increased for a short time. The increasedpressure thus also acts in the working-fluid line and in inlet 14 ofvalve 9. Since the spring force generated by pressure spring 25 issmaller than the force acting on valve body 18 as a result of theincreased pressure, valve body 18 is moved further in the direction offlow until sealing element 22 of region 20 lies against inlet-sidesealing seat 24 of diaphragm 16. Throughflow opening 17 is thus closedso that no fuel reaches the suction jet pump during the startingprocess.

Valve 9 shown in FIG. 5 differs from the valve according to FIG. 2 inthe arrangement of pressure spring 25. Pressure spring 25 is supportedbetween diaphragm 16 and region 20 of valve body 18. Region 20 possessesa shoulder 26 for this purpose. Shoulder 26 is used on the one hand as aguide for pressure spring 25 and ensures on the other hand sufficientspace in the axial extension if pressure spring 25 is compressed.

FIG. 6 shows valve 9 with a tension spring 27 which is fastened on theinlet side between housing 13 and valve body 18 and moves valve body 18in the depressurized state counter to the direction of flow such thatsealing element 21 interacts with sealing seat 23 of diaphragm 16 suchthat valve 9 is closed.

In a further configuration, FIG. 7 shows valve 9 in the case of systempressure. Herein, two pressure springs 25, 28 are arranged on the outletside. Pressure spring 25 behaves in accordance with its design as inFIGS. 2 to 4. Pressure spring 28 is harder and is designed with ashorter length, wherein the length and the spring rigidity of pressurespring 28 are selected such that, in the case of system pressure, valvebody 18 is moved in the direction of flow as a result of the forceacting on it until it lies against pressure spring 28 without pressurespring 28 being compressed. Valve 9 in an open position is located inthis position. In this manner, a defined position is created for valvebody 18 in the case of system pressure. In the case of a furtherpressure increase in the event of a starting process, the force actingon valve body 18 is larger than the spring forces of pressure springs25, 28 such that the valve behaves as in FIG. 4.

1.-10. (canceled)
 11. A suction jet pump, the suction jet comprising: adriving jet nozzle; a mixing tube arranged downstream of the driving jetnozzle; an intake opening arranged between the mixing tube and thedriving jet nozzle; a working-fluid line coupled to the driving jetnozzle; and a valve arranged in the working-fluid line, the valvecomprising: a valve housing, having an inlet and an outlet, athroughflow opening arranged in the housing between the inlet and theoutlet; a valve body arranged on both sides of the throughflow opening,the valve body adapted to close the throughflow opening on an inlet sideand on an outlet side; and at least one spring arranged within thehousing and coupled to the valve body, wherein the at least one springis adapted to hold the valve body in a position closing the throughflowopening until the system pressure is reached.
 12. The suction jet pumpaccording to claim 11, wherein the throughflow opening is a diaphragm.13. The suction jet pump according to claim 11, wherein the valve bodycomprises: a first sealing element; and a second sealing element,wherein the first sealing element and the second sealing element areadapted to cooperate with a respective inlet sealing seat and outputsealing seat on the inlet side and the outlet side of the throughflowopening.
 14. The suction jet pump according to claim 13, wherein thefirst sealing element and the second sealing element are annular disks.15. The suction jet pump according to claim 12, wherein a first sealingelement and a second sealing element are arranged on both sides of thediaphragm relative to the direction of flow such that the first sealingelement and the second sealing element surround the throughflow opening16. The suction jet pump according to claim 11, further comprising asecond spring arranged within the housing and coupled to the valve body,wherein the first spring is designed with respect to the openingpressure of the valve and the second spring allows a further movement ofthe valve body only above the system pressure.
 17. The suction jet pumpaccording to claim 11, wherein the at least one spring is a pressurespring.
 18. The suction jet pump according to claim 11, wherein the atleast one spring is a tension spring.
 19. The suction jet pump accordingto claim 17, wherein the at least one spring is arranged between thehousing and the valve body.
 20. The suction jet pump according to claim17, wherein the at least one spring is arranged between the valve bodyand the throughflow opening.
 21. The suction jet pump according to claim11, further comprising a shoulder formed on the valve body for receivingthe at least one spring.
 22. The suction jet pump according to claim 11,wherein the at least one spring is adapted to hold the valve body in aposition closing the throughflow opening on the outlet side until thesystem pressure is reached.
 23. The suction jet pump according to claim18, wherein the at least one spring is arranged between the housing andthe valve body.
 24. The suction jet pump according to claim 11, whereinthe at least one spring is adapted to hold the valve body in a positionclosing the throughflow opening on the inlet side until the systempressure is reached.
 25. A suction jet pump, the suction jet comprising:a driving jet nozzle; a mixing tube arranged downstream of the drivingjet nozzle; an intake opening arranged between the mixing tube and thedriving jet nozzle; and a valve coupled to the driving jet nozzle in theworking-fluid line, the valve comprising: a valve housing having aninlet and an outlet, a throughflow opening arranged in the housingbetween the inlet and the outlet, the throughflow opening having aninlet sealing seat on an inlet side and an output sealing seat and anoutlet side of the throughflow opening; a valve body having a firstsealing element arranged on the first side of the throughflow openingand a second sealing element arranged on the second side of thethroughflow opening, the first sealing element and the second sealingelement are adapted to cooperate with the respective inlet sealing seatand output sealing seat to close the throughflow opening on one of theinlet side and the outlet side of the throughflow opening; and at leastone spring arranged within the housing and coupled to the valve body,wherein the at least one spring adapted to hold the valve body in aposition closing the throughflow opening until the system pressure isreached.
 26. The suction jet pump according to claim 25, wherein the atleast one spring adapted to hold the valve body in a position closingthe throughflow opening on the outlet side until the system pressure isreached.
 27. The suction jet pump according to claim 25, wherein the atleast one spring adapted to hold the valve body in a position closingthe throughflow opening on the inlet side until the system pressure isreached.